@Sobachatina's answer is correct, but I just would like to add this (since you asked the shortest cooking time):

in my country cans of red kidney beans are available. These are in some kind of liquid, so you do have to rinse them. Other than that, no work with the beans anymore. They are already soft and ready to eat.

To be honest, I'm not even sure the rinse part is necessary, but I just do.

That liquid is the starch from the beans absorbed into the water. It's not harmful, but it is sort of slimy. When I'm doing beans and rice, I like to gravity drain the slime in a colander, but not rinse. When I'm doing a bean salad, I rinse them completely.
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Chris CudmoreNov 23 '11 at 19:58

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@Chris- just starch? I would assume that there would be a lot of protein in there as well.
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SobachatinaNov 23 '11 at 20:07

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A quick perusal of the Googlenet indicates it's mostly starch, and apparently some indigestible sugars which may cause gas.
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Chris CudmoreNov 23 '11 at 20:11

If you have, ahhh - digestive troubles - with beans, this is the preferred way to prepare dried beans for use in most recipes that call for them. [Science here.] Some claim that it impacts flavor or texture as opposed to the slow soak, but I haven't found this to be the case.

To rehydrate:

Figure out how much of the dried beans you need. Here's a good conversion guide.

Sort the beans on a dry paper towel. Dried beans will often have stones, clumps of dirt, broken or withered beans, twigs and other detritus from harvesting.

Put the beans in a good sized pot, and cover with about three inches of water.

Bring to a roiling boil. As soon as it's roiling, take the pot off the heat, and leave it to sit for an hour.

Dump in a colander and rinse well.

To cook:

Dump the beans back into the rinsed pot.

Cover with 3 inches of water

Add a pinch of salt and a bay leaf to the water to season.

IMPORTANT: If you have hard water (it leaves a white residue on your stainless steel cookware after washing), you will need to add a quarter to a full teaspoon of baking soda, otherwise the beans will be too firm, and no amount of simmering will ever get them tender enough to eat.

Bring the beans to a roiling boil.

Back off the heat to medium-low as soon as it's roiling, and simmer for an hour. Test the beans - if too firm, simmer further to your preference. I find I like the skins just about split, very tender - around 90 minutes.

The beans are now ready to use in your recipe. I find the taste, tenderness and texture of beans prepared this way to be superior to canned beans, which seem mealy and bland to me.

I use 1 cup of kidney beans to about 3 1/2 cups boiled water, put in a pressure cooker & cook for about 8 whistles to soften. To make Rajma: in a separate pot sweat off onion, cumin seeds garlic & ginger - add spices: coriander powder, tumeric, chilli powder, & garam masala. Add 1 400g tin of chopped tomatoes ( I add 1 cube of dried veg stock or 1 tsp), let simmer. Once the beans are cooked ( let the pressure out & test the beans to make sure they are soft) add to the pot of tomatoes and spices including the dark red water that the beans have cooked in, reduce & stir 5-10 mins so it doesn't stick to the bottom & burn. Reducing the sauce will make it thicker so stop reducing when you have reached the consistency you are happy with. Taste, season & enjoy! Make fresh rotis with chapati flour & water for an authentic meal.

*Spices & Cumin seeds about 1 level tsp each depending on how spicy you like it.